Unfortunately, you did not mention anything about the version of Team Viewer you are using and including the operating system your computer is running on. But anyway, since reinstalling it seems useless, try checking your computer for any possible errors. It is possible that there is an error in the file system that is blocking or is interfering with the connection. Use a disk utility application to check the system. For a much thorough diagnostics on the system, use a disk utility application like Norton Utilities, PC Tools Performance Toolkit, or Norton System Works.
You may also try checking if your computer has a stable internet connection. If there seems to be no problem with the connection, try upgrading your current version of Team Viewer. Team Viewer Portable 7.0.12799 is already available at http://portableapps.com/apps/utilities/teamviewer_portable. This version is compatible with Windows 2000, Windows XP, Windows Vista, and Windows 7.
This problem is probably caused by a rambled license or change of your Mac address.
Check for consistencies. After that, uninstall Teamviewer.
Once the software is uninstalled, click Run from Start or Windows + R on your keyboard and type: %appdata% and hit enter.
This command will delete the whole installation folder including the leftovers of the program.
Next step is to delete the registry folder which can be done by typing "regedit" without double quotes in the Windows Run.
Click on the HKEY_CURRENT_USER node, then Software, Teamviewer, right-click on the node and select delete.
Then, clean the computer's registry using registry cleaners like Ccleaner.
Once everything is done, install Teamviewer. Upon installation, be careful not to forget to tick on "Personal Use".